1. Field of the Invention
The present invention relates to a rotation speed detecting device for a recording and reproducing apparatus, and a method therefor, and in particular to a rotation detecting device for a recording and reproducing apparatus which can exactly detect a rotation speed of a rotation member which is rotated at a high or low speed, and a method therefor. More particularly, the present invention relates to a rotation detecting device for a recording and reproducing apparatus and a method therefor which can easily precisely detect a rotation speed of a reel during a high- or low-speed rotation, and which can exactly detect a rotation speed of a motor of an optical disc recording and reproducing apparatus, by forming in a series equational division method a wing unit and a space unit of a sensor detecting member which is protrusively formed in a single body at a supply reel and a take-up reel of the recording and reproducing apparatus, such as a VCR.
2. Description of the Background Art
FIG. 1 is a schematic view illustrating an inside structure of a VCR which is a general recording and reproducing apparatus.
A capstan shaft 11 rotated to play a tape is provided at one side of a drum 10 including a rotation head, and a capstan pulley 12 rotated in a single body with the capstan shaft 11 is installed at the capstan shaft 11.
A pulley gear 13 is provided separately from the capstan pulley 12 by a predetermined distance. The pulley gear 13 is connected to the capstan pulley 12 by a belt 14, and thus a rotation of the capstan pulley 12 is transferred thereto.
At one side of the pulley gear 13 is provided an idle gear 15 engaged with the pulley gear 13, and moved and rotated to the right or left side in accordance with an operational mode of the recording and reproducing apparatus.
A supply side intermediate gear 16 and a take-up side intermediate gear 17 are provided at the right and left sides of the idle gear 15, respectively, and engaged with the idle gear 15 according to a right- or left-direction movement of the idle gear 15.
In addition, a supply reel 1 is provided to be engaged with the supply side intermediate gear 16, and a take-up reel 2 is disposed to be engaged with the take-up side intermediate gear 17. Accordingly, a rotation of the idle gear 15 is transferred to the supply side intermediate gear 16 or take-up side intermediate gear 17, thereby rotating the supply reel 1 or the take-up reel 2.
On the other hand, a rotation detecting device is provided to the recording and reproducing apparatus including the above-described components, in order to detect a rotation speed of the supply reel and the take-up reel when the tape is moved by a capstan motor. It will now be explained with reference to FIGS. 2 to 5.
FIG. 2 is a perspective view illustrating a detecting sensor measuring a rotation speed of the supply reel and the take-up reel for the general recording and reproducing apparatus. FIG. 3 is a circuit view illustrating a circuit constitution of the general detecting sensor. FIG. 4 is a perspective view illustrating a conventional sensor detecting member formed at a supply reel and a take-up reel for a general magnetic recording and reproducing apparatus. FIG. 5 is a graph showing an operational pulse in accordance with a conventional rotation speed detecting device.
Referring to FIGS. 2 to 5, in the rotation detecting device detecting a rotation speed of the supply reel and the take-up reel for the general recording and reproducing apparatus, a detecting sensor 7 including a light emitting unit 8 and a light receiving unit 9 as shown in FIG. 2 is disposed at each one side of the lower portions of the supply reel 1 and the take-up reel 2, and a ring-shaped sensor detecting member 20 is formed in a single body at the lower surfaces of the supply reel 1 and the take-up reel 2.
Here, a plurality of wing strips 30 and a plurality of space parts 40 which have an identical width (W.sub.1 =W.sub.2) are alternately formed at the lower portion of the sensor detecting member 20 in accordance with the equational division method. The plurality of wing strips 30 and the plurality of space parts 40 are positioned between the light emitting unit 8 and the light receiving 9 of the detecting sensor 7, rotated when the supply reel 1 or the take-up reel 2 is rotated, and passed between the light emitting unit 8 and the light receiving unit 9 of the detecting sensor 7.
The rotation detecting device, namely the detecting sensor 7 and the sensor detecting member 20 may be provided at the supply side intermediate gear 16 and the take-up side intermediate gear 17, respectively.
Reference mark Vcc denotes a voltage, R.sub.1, R.sub.2, R.sub.3 denote resistances, and C.sub.1 denotes a condenser.
The operation of the recording and reproducing apparatus including the above-described rotation detecting device, and the rotation speed detecting operation of the rotation detecting device will now be described.
When an operational command is provided to the recording and reproducing apparatus, the capstan shaft 11 is rotated. As the capstan shaft 11 is rotated, the capstan pulley 12 formed in a single body with the capstan shaft 11 is rotated.
When the capstan pulley 12 is rotated, the pulley gear 13 connected to the capstan pulley 12 by the belt 14 is rotated, and thus the idle gear 15 engaged with the pulley gear 13 is rotated. Here, the idle gear 15 is moved to the right or left side according to an initial operational command, and then rotated.
Thereafter, the idle gear 15 is moved to the right or left side, and thus selectively engaged with the supply side intermediate gear 16 or the take-up side intermediate gear 17 respectively disposed at the left and right sides thereof. As a result, the supply side intermediate gear 16 or the take-up side intermediate gear 17 is rotated, and thus the supply reel 1 or the take-up reel 2 engaged respectively with the supply side intermediate gear 16 or the take-up side intermediate gear 17 is rotated.
Accordingly, as the supply reel 1 or the take-up reel 2 is rotated, the sensor detecting member 20 formed in a single body at the lower surface of the supply reel 1 or the take-up reel 2 is rotated, and thus the plurality of wing strips 30 and the plurality of space parts 40 of the sensor detecting member 20 are alternately passed and rotated between the light emitting unit 8 and the light receiving unit 9 of the detecting sensor 8.
Therefore, when the detecting sensor member 20 is passed and rotated through the detecting sensor 7, if the space part 40 is passed therethrough, a light generated from the light emitting unit 8 of the detecting sensor 7 is transmitted to the light receiving unit 9, and thus a microcomputer (not shown) disposed at a circuit unit recognizes a rotation of the supply reel 1 or the take-up reel 2.
Since the conventional detecting sensor member 20 includes the plurality of wing strips 30 and the plurality of space parts 40 having an identical width (W.sub.1 =W.sub.2) according to the equational division method, if the wing strips 30 and the space parts 40 are widely formed, and the supply reel 1 or the take-up reel 2 is rotated at a high speed, the sensor detecting member 20 can detect the rotation of the supply reel 1 or the take-up reel 2, and transmit a data in order for the microcomputer (not shown) to recognize the rotation without an error. However, in the case of a slight rotation of 1/10.about.1/20, the detecting sensor 7 can detect the rotation only when a rotation angle of the supply reel 1 or the take-up reel 2 is increased. In case the rotation angle of the supply reel 1 or the take-up reel 2 is small, the wing strip 30 or the space part 40 is positioned at the detecting sensor 7, and thus the detecting sensor 7 is not varied.
That is to say, when at least a pair of wing strip 30 and space part 40 of the sensor detecting member 20 is passed between the light emitting unit 8 and the light receiving unit 9 of the detecting sensor 7, the detecting sensor 7 can detect the rotation.
To the contrary, when the wing strip 30 and the space strip 40 of the detecting sensor 20 are narrowly formed, the supply reel 1 or the take-up reel 2 is slightly rotated, the microcomputer can be operated without an error. However, at a high-speed rotation, a passing speed is also high, and thus a light from the light emitting unit 8 of the detecting sensor 7 cannot be sufficiently transmitted to the light receiving unit 9 thereof, and does not reach to a reference voltage. Accordingly, the microcomputer (not shown) cannot recognize the rotation of the reel.
As a result, a strip width of the detecting sensor member is determined by taking an average value of the recognition values of the microcomputer according to the rotation speed, and thus an optimal state of performance cannot be embodied. In addition, it is disadvantageous to maintain two kinds of units in accordance with a property of a model.